Hitting a New Low: The Unique 28 h Cessation of Accretion in the TESS Light Curve of YY Dra (DO Dra)

Abstract

We present the Transiting Exoplanet Surveying Satellite (TESS) light curve of the intermediate polar YY Draconis (YY Dra, also known as DO Dra). The power spectrum indicates that while there is stream-fed accretion for most of the observational period, there is a day-long, flat-bottomed low state at the beginning of 2020 during which the only periodic signal is ellipsoidal variation and there is no appreciable flickering. We interpret this low state to be a complete cessation of accretion, a phenomenon that has been observed only once before in an intermediate polar. Simultaneous ground-based observations of this faint state establish that when accretion is negligible, YY Dra fades to $g=17.37\pm 0.12$, which we infer to be the magnitude of the combined photospheric contributions of the white dwarf and its red dwarf companion. Using survey photometry, we identify additional low states in 2018-2019 during which YY Dra repeatedly fades to -- but never below -- this threshold. This implies relatively frequent cessations in accretion. Spectroscopic observations during future episodes of negligible accretion can be used to directly measure the field strength of the white dwarf by Zeeman splitting. Separately, we search newly available catalogs of variable stars in an attempt to resolve the long-standing dispute over the proper identifier of this system.

12 pages, 4 figures, submitted to the Astronomical Journal and reviewed favorably

References in corpus (16)

• The Transiting Exoplanet Survey Satellite
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0
• The Catalina Surveys Periodic Variable Star Catalog
• Measuring the masses of magnetic white dwarfs: A NuSTAR Legacy Survey
• Magnetically gated accretion in an accreting 'non-magnetic' white dwarf
• Quasi-periodic oscillations in the TESS light curve of TX Col, a diskless intermediate polar on the precipice of forming an accretion disk
• Return of the King: Time-Series Photometry of FO Aquarii's Initial Recovery from its Unprecedented 2016 Low State
• PALOMA: A Magnetic CV between Polars and Intermediate Polars
• An accreting white dwarf displaying fast transitional mode switching
• Multiple time scales in cataclysmic binaries. The low-field magnetic dwarf nova DO Draconis
• The true nature of Swift J0746.3-1608: a possible Intermediate Polar showing accretion state changes
• Rapid bursts of magnetically gated accretion in the intermediate polar V1025 Cen
• Optical spectra of FO Aquarii during low and high accretion rates
• New observations of DW Cnc: where is the 38 min signal?
• The Magnetic Cataclysmic Variable LSQ1725-64

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• Kepler K2 and TESS observations of two magnetic cataclysmic variables: The new asynchronous polar SDSS J084617.11+245344.1 and Paloma
• Short Duration Accretion States of Polars as seen in TESS and ZTF data
• Serendipitous discovery of the magnetic cataclysmic variable SRGE J075818-612027
• Confirmation of SRGt 062340.2-265751 as a nova-like cataclysmic variable with a possible magnetic nature